The GELLAB-II software system is an exploratory data analysis system for the analysis of sets of 2D electrophoretic protein gel images. It incorporates sophisticated subsystems for image acquisition, processing, database manipulation, graphics and statistical analysis. It has been applied to a variety of experimental systems in which quantitative and qualitative changes in one or more proteins among hundreds or thousands of unaltered proteins is the basic analytic problem. Keeping track of changes detected using these methods is also a major attribute of the system. A composite gel database may be "viewed" under different exploratory data analysis conditions and statistical differences and subtle patterns elucidated from "slices" of an effectively 3D database. Results can be presented in a variety of tables, plots or derived images and on workstations over wide area networks. The GELLAB-II research has resulted in a technology transfer CRADA with CSPI/Scanalytics Inc. for a commercially available system GELLAB-II+ making this technology easily available to cancer researchers on inexpensive Microsoft Windows PCs (released in 1996). Such commercialization results in wider use and better support of the GELLAB-II technology than we can provide. GELLAB-II applications this period include: ongoing studies of nuclear matrix protein changes in prostate cancer to aid screening and staging of men with prostate cancer (J.Hopkins); and Rett syndrome (CDC) Robinson MK etal. Electrophoresis 1995;16:1176-83. In the prostate cancer studies, we are looking for both missing proteins as well as subtle quantitative changes in patterns on sets of proteins which correlates with experimental conditions and staging and screening of men with prostate cancer. We are also doing a similar investigation of nuclear matrix protein patterns from renal cell carcinoma. The Hopkins group's prostate molecular work has identified several of the protein spots by sequence analysis and are completing studies to confirm these sequences.